The association says natural gas is $1.50 to $2 cheaper per gallon than diesel and produces fewer greenhouse gas emissions. So one of the goals of Thursday's event is to encourage the conversion of more truck fleets to natural gas.

MTA President John Hausladen says many trucking companies can recoup their investment in just a few years and cut their fuel costs by up to 50 percent by making the switch. And he says natural gas has emerged as a viable truck fuel largely without the help of government subsidies.